Improve JSON rendering in markdown logs with syntax highlighting

- Replace tildes (~~~) with triple backticks for standard markdown
- Add 'json' language hint for syntax highlighting
- Update comments to reflect json code block usage
- Update tests to expect ```json instead of ~~~

Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

Author: Copilot

internal/logger/rpc_logger.go

@@ -184,7 +184,7 @@ func isEffectivelyEmpty(data map[string]interface{}) bool {
 
 // formatRPCMessageMarkdown formats an RPC message for markdown logging
 func formatRPCMessageMarkdown(info *RPCMessageInfo) string {
-	// Concise format: **server**→method \n~~~ \n{formatted json} \n~~~
+	// Concise format: **server**→method \n```json \n{formatted json} \n```
 	var dir string
 	if info.Direction == RPCDirectionOutbound {
 		dir = "→"
@@ -210,9 +210,9 @@ func formatRPCMessageMarkdown(info *RPCMessageInfo) string {
 		if isValidJSON {
 			// Don't show JSON block if it's effectively empty (only params: null)
 			if !isEmpty {
-				// Valid JSON: use code block for better readability (pretty printed)
-				// Empty line before ~~~ per markdown convention
-				message += fmt.Sprintf("\n\n~~~\n%s\n~~~", formatted)
+				// Valid JSON: use json code block for syntax highlighting (pretty printed)
+				// Empty line before code block per markdown convention
+				message += fmt.Sprintf("\n\n```json\n%s\n```", formatted)
 			}
 		} else {
 			// Invalid JSON: use inline backticks to avoid malformed markdown

internal/logger/rpc_logger_test.go

@@ -194,7 +194,7 @@ func TestFormatRPCMessageMarkdown(t *testing.T) {
 				PayloadSize: 50,
 				Payload:     `{"jsonrpc":"2.0","method":"tools/list","params":{}}`,
 			},
-			want:    []string{"**github**→`tools/list`", "~~~", `"params"`, "{}"},
+			want:    []string{"**github**→`tools/list`", "```json", `"params"`, "{}"},
 			notWant: []string{`"jsonrpc"`, `"method"`},
 		},
 		{
@@ -206,7 +206,7 @@ func TestFormatRPCMessageMarkdown(t *testing.T) {
 				PayloadSize: 100,
 				Payload:     `{"result":{}}`,
 			},
-			want:    []string{"**github**←`resp`", "~~~", `"result"`},
+			want:    []string{"**github**←`resp`", "```json", `"result"`},
 			notWant: []string{`"jsonrpc"`, `"method"`},
 		},
 		{
@@ -232,7 +232,7 @@ func TestFormatRPCMessageMarkdown(t *testing.T) {
 				Payload:     `{invalid json syntax}`,
 			},
 			want:    []string{"**github**→`tools/call`", "`{invalid json syntax}`"},
-			notWant: []string{"~~~"}, // Should NOT use code blocks for invalid JSON
+			notWant: []string{"```json"}, // Should NOT use code blocks for invalid JSON
 		},
 		{
 			name: "request with only params null after field removal",
@@ -245,7 +245,7 @@ func TestFormatRPCMessageMarkdown(t *testing.T) {
 				Payload:     `{"jsonrpc":"2.0","method":"tools/list","params":null}`,
 			},
 			want:    []string{"**github**→`tools/list`"},
-			notWant: []string{"~~~", `"params"`}, // Should NOT show JSON block when only params: null
+			notWant: []string{"```json", `"params"`}, // Should NOT show JSON block when only params: null
 		},
 		{
 			name: "request with empty object after field removal",
@@ -258,7 +258,7 @@ func TestFormatRPCMessageMarkdown(t *testing.T) {
 				Payload:     `{"jsonrpc":"2.0","method":"tools/list"}`,
 			},
 			want:    []string{"**github**→`tools/list`"},
-			notWant: []string{"~~~"}, // Should NOT show JSON block when empty
+			notWant: []string{"```json"}, // Should NOT show JSON block when empty
 		},
 	}